Dry oil-free screw air compressor is a twin-screw air compressor. There is no lubrication in the compression chamber of oil-free screw compressor, only lubricating oil in the gear box, so it can be said that it is dry. The surface of the rotor is specially coated, and the Yin and Yang rotors do not really touch each other. Oil-free dry screw is not contacted, so the first compression pressure is not very high. In order to improve the pressure, two-stage compression is used. The best compression effect is isothermal compression, which is impossible to achieve in practice. Therefore, after the first stage compression, there are intermediate coolers and traps (cooling, drainage), and after the second stage compression, there are also rear coolers. The pressure of the first stage compression is about √2, and then the pressure enters the second stage compression. Because of the high speed and the high temperature in the nose, the nose shell is a disposable lost foam technology for cooling. The nose housing is completely separated from the rotor. If it is air-cooled, the shell is oil-cooled; if it is water-cooled, the shell is water-cooled.